Rotary pump



Feb. 16, 1943. D. A. FULTON ROTARY PUMP Filed Sept. 18, 1939 I INVENTOR. awe/o 1,4 Fez/an ATTORNEY;

Patented Feb. 16,' 1943 UNITED STATES FFECE 13 Claims.

It is a further object of my invention to produce a compressor of the rotary type which is compact, efiicient, dependable, and has a long life.

These and other objects of my invention will become apparent from the following description of preferred forms thereof, and from the drawing illustrating those forms, in which:

Fig. 1 is an axial cross-sectional View of one form of compressor made according to my invention,

Fig. 2 is a. cross-sectional view taken at 22 in Fig. 1,

Fig. 3 is an axial cross-sectional View of another form of compressor embodying my invention, and

Fig. 4 is a cross-sectional view taken at 4-4 in Fig. 3.

Referring now to the drawing, and particularly to Fig. 1 thereof, the numeral It indicates a housing provided with a cylinder II open at one end (the left end in Fig, 1). A cap I2 is bolted or otherwise securely fastened over the open end of cylinder I I closing it with a sealing fit. The end of the cylinder formed by the housing If! is preferably normal to the axis of the cylinder and is provided with a convex conical surface I3 (hereinafter referred to as the cone I3) coaxial with the cylinder I I extending into the same. The diameter of the base of the cone I3 is somewhat less than that of the cylinder II thus leaving a small annular shoulder I4 surrounding the base of the cone.

Within the cylinder II, and making a sealing fit with the wall and shoulder I4 thereof, I provide a rotor IE, to which is attached a shaft I6 extending outwardly through the cap I2. To provide a sealing fit, the rotor has a cylindrical shape, and to make even more certain that a fluid-tight seal is obtained, I may provide grooves I1 and Ila around the periphery of the rotor and insert sealing rings I8 and Ilia therein. It will be apparent that a greater or lesser number of sealing rings may be used, as will be pointed out more fully hereinafter, or that other types of sealing means may be used; however, I have found the means illustrated to be a very satisfactory method and give it by way of example.

In order for the rotor I5 to bear against the shoulder IA of the recess II-, it is necessary to provide the end face of the rotor with a recess into which the cone I3 may fit. It is this'recess within the end of the rotor, together with the cone I3 which provides the compressor action of my device. I am aware that others have developed pumps for liquids making use of a convex cone-shaped surface against which an 0bliquely truncated cylinder bears, but such pumps are not suitable for gas compressors of the type used for refrigerators because of the high pressures involved and the resultant leakage, of gas. To overcome these disadvantages, Iform the end surface of the rotor I5 in the shape of an obliquely-positioned concave cone 20. Whose apex is substantially coincident with the apex: of the cone I3, and the length of whose side is equal to the length of the side of cone I3.

The shape and aspect of the conical surface 293 is such that it provides a cam-shapediend surface, one of Whose generating elements makes wiping contact with the cone I3, said, element being hereinafter referred to as the high point of the end surface 26. The base of the concave conical surface 20 is a plane circle angularlypositioned with respect to both the shoulder I4 and the axis of the rotor I5, and hence must lie within the body of the rotor except at the high point. This requirement necessitates a lip 2|, of varying height, and for reasons which will be apparent later, the inner surface of this lip should be shaped in the form of a portion of a sphere whose center is at the apex of the concave conical surface 20 and whose radius is equalto the length of' one of the sides of that cone.

Thus there is formed a chamber of constant volume between the cone I3 and the concave conical end surface 23; and as the rotor I5 is. revolved, the position of the chamber revolves with it but does not change in volume, since the angular aspect of the end surface 20 with respect to the axis of the rotor does not vary. Any fluid within the chamber would therefore be carried around with the rotor and neither compressed. nor expanded. However, if a plate 22, in the form of a minor circular sector whose apex angle is equal to the apex angle of the concave conical surface 20 and whose radius is equal to the length of one of the sides of said conical surface, is placed in a slot 23 extending diametrically across the cone l3 and shaped in the form of a sector of the same circle as that of the plate 22, the latter will divide the chamber into two or three chambers, depending on the location of the high point of the end surface 20. The plate 22 is free to oscillate back and forth in an arc of the circle of which it is a sector; and since its apex angle is equal to the apex angle of the end surface 28, the radial edges of the sector will bear and wipe against the end surface at all times. the high point of the end surface 20 approaches one of the radial edges of the plate 22, that edge is forced into the body of the cone l3, and the other radial edge moves out of the cone and wipes against the concave conical end surface 20,

Thus as the convex conical surface 13 and decrease the volume of the chamber, compressing any fluid therein and forcing it out the exhaust passageway 3|. At the same time, fluid is being drawn into an expanding chamber immediately behind the high point as first described. This cycle is completed twice each revolution of the rotor l5, once on either side of the plate 22, and thus a substantially constant flow of fluid is maintained.

As the rotor I5 revolves, the fluid is drawn into the chamber between the end surface 20 and the cone l3, and then compressed, as previously described. However, because of th increase of volume of the first chamber after the intake pasisageway 30 has passed the plate '22, more fluid may be drawn into that chamber, and hence to secure the'maximum efiiciency of the compressor,

' I prefer to provide an auxiliary intake passageuntil the high point contacts the first-mentioned radial edge of the plate 22, when that edge of the plate is in its innermost position, and the other radial edge is in its outermost position.

It will now be seen that as the radial edge of the plate 22 moves outwardly and into the rotor IS, a portion of its arcuate edge follows it and extends out from the cone [3 and into the rotor, wiping against the inner surface of the lip 2|. For this reason, since the arcuate edge is formed in the shape of a portion of an arc of a circle, and the rotor l5 revolves about an axis perpendicular to the axis of the arc of the circle of the plate, it is necessary for the inner surface of the lip 2| to be formed in the shape of a por- ,tion of a sphere in order for the plate 22 to make sealing contact with it.

In order for the device to function as a compressor, it is necessary to provide intake and outlet means so that fluids may enter and leave the chambers-formed by the conical surfaces l3 and 20, lip 2l, ar1d the oscillating plate '22. In Fig. 1, I have illustrated one method of doing this which is particularly well adapted for use with the sealing means shown there. In this method, I providethe periphery of the rotor I5 with grooves 24 and 25, hereinafter referred to as the intake and outlet grooves, respectively; and aligned with these grooves, I provide apertures 26 and 21 in the housing l leading to intake and exhaust connections 28 and 29, respectively. A short distance from the high point of the end surface 20, measuredinthe direction opposite from the rotation of the rotor IS, a passageway 30 leads from the end surface 20 to the intake groove 24, and a similar passageway 3| leads from a point a short distance in advance of the high point of the camshaped surface to the exhaust groove 25.

Thus as the rotor l revolves and the high point of the end surface passes over the plate 22 and continues on, an expanding chamber is created behind the high point, bounded by the end surface 20, the convex conical surface IS, the inner surface of the lip 2|, and the plate 22. As the volume of the chamber increases, the suction created thereby causes fluid to flow in through the inlet passageway and fill the expanding chamber. This continues until the passageway 30 crosses the opposite radial edge of the plate 22, when the same action takes place on the opposite side of the plate. As the rotor then revolves for approximately one half a revolution, the volume of the first chamber increases somewhat because of, the oblique aspect of the end surface 20. Then when the high point of the cam-shaped surface again crosses the plate 22 into the firstmentioned chamber, the high point wipes against way 33a,.spaced approximately diametrically opposite from the outlet passageway 3| so that both will not be open to the same chamber at the same time. Thus after the main intake passageway 30 has crossed the plate 22 into the other chamher, the auxiliary intake passageway 30a remains open to the first chamber, permitting a pressure equilibrium to be established between the first chamber and the supply line. g

It will be apparent that'for the proper functioning of the device, it is important that a fluid-tight seal be maintained between the plate 22, and the end surface 20 so that fluid being compressed on one side of the platewill not escape to the opposite side of the plate where fluid is being drawn in. It is to provide this fluid-tight seal that I have made the end surface 20 in the form of an oblique cone, for in this way, I am able to transversely curve the radial edges of the plate 22 to conform to the curvature of the concave conical surface 20. By thus curving the plate 22, I provide an area of contact instead of a line of contact between the plate and the concave conical surface 20. If the end surface 20 were made in the form; of an obliquely truncated cylinder, the plate would make only a line contact with the end surface and much of the sealing effect would be lost. Others have attempted to usetruncated cylinders and overcome said disadvantage by providing an auxiliary pivoted wiping plate attached to the sector plate and making sealing contact with the cam-shaped surface, but such devices have proven impractical, and are unnecessary in my type of rotor employing a cone-shaped surface.

} Theapex angle of the cone I3 is not critical, though it is preferable that it be of such a value that the sides of the cone do not present a very sharp angle to the plane of the lip 2|. If this latter angle is too acute, any slight amount of wear of the end of the rotor [5 will permit an excessive amount of leakage, while if the angle is not so acute, leakage is kept to a minimum. The size and aspect of the apex angle of the concave conical surface will be determined to a certain extent by the size of the apex angle of the cone l3, since the high point of the cam-shaped surface 20 must make sealing contact with the cone 13. The apex angle of the concave conical surface 29 will of course determine the apex angle of the plate 22, but the other angles may be varied. The relative sizes of the apex angles of the conical surfaces l3 and 20 and the length of their sides will determine the displacement of the compressor, which, of course, may be varied over wide limits.

As previously mentioned, sealing rings l8 and v[8a are placed in grooves 11 and I la around the periphery of the rotor, and serve -thedouble purpose of sealing the fluid within the chamber formed by the two conical surfacesl3- and--20, and also preventing the escape of the; compressed fluidfromthe exhaust groove 25 tothe intake .groove 24. Ifthe pressure inthe intake groove 24 is substantially above or below --atmospheric pressure, it maybe advisable to place a sealing ring or rings between it andendof-the-rotor l; and likewise'it may be preferable-to place a plurality of sealing rings *betweenthe intake and outlet grooves 24- ahd- 25 andlor-between the outlet groove -25-andthe inner end of the rotor 15. Suchconsiderations, cf-course; will depend upon the pressures involved and the closeness of fit between the rotor [hand the housing 10, and will be apparent-tothose skilledin the art.

Because of the mechanical problems involved, it may be difiicult to form the inner surface of the lip 2l=in the shape ofqa portion of a'sphere; and hence in- Figs. 3 and :4, I show a-form of compressor made according to'my invention in which I dispense with-said lip. Theform illustrated insaidfigures is similar in most respects to the form shown in-Figs. l and 2, and'has ahousing II), a cap l2, a cone l3,"arotor l-5 to Which-is attached a shaft I6, an obliquely-positioned concave conical surface 20, a-plate 22 in the form of a minor circular sector, and a slot 23 in the cone I 3 in which the plate 2-2'is'located, as previously described in detail. Instead of-the cylinder I I, however, this form of mycompressor-is provided with a chamber -4EI- shaped in :the form of a portion of a sphere-having its axis coincident with that of the rotor 15. Theperiphery of the rotor l5'adiacent the endsurface '2-0 is therefore complementally shaped so as to provide a se'aling fit with the walls of the recess 40. The radius of the spherical surfaces is equal to the length of thesides of the conical surfaces l3 and-20, and the center iscoincident withthe apices of'the two conical surfaces. Hence-sincethe-plate 22 has the same radius and center,- it will make-a sealingand wiping fitwith the spherical surface 40 of the housing If), and a similar fit with the end surface 20 of the rotor 15. this way, I have eliminated the need for thelip-2| and shoulder I4, or as an alternative, the need for a groove in the side of the chamber in which the plate 22 may move when a cylindrical chamber and rotor are used. The need for a groove in the side of the chamber in lieu of the lip 2|, will be apparent when it is remembered that the end surface 20 is obliquely positioned and the rotor is a cylinder; and hence the distance along the cam-shaped surface from the apex of the cone to the edge of the rotor will vary as the angle the end surface 320 makes with the side of the rotor varies. Therefore, since the plate 22 must make sealing contact with the end surface 20 along its greatest dimension as well as all others, provision must be made for the excess length of the radial edge of the plate 22 to move into the walls of the housing II! when it is not needed.

If recourse is had to the side groove just mentioned, there will be a line of contact between the rotor l5 and the plate 22 preventing the fluid from escaping through the groove and around the plate, and as soon as there has been a sufiicient amount of wear, the compression is lost. To avoid .this difiiculty, I have found it best to use either the lip and shoulder method shown in Figs. 1 and 2, or preferably, the spherically-shaped rotor of Figs. 3 and 4.

Inconjunction with thelatterform; I have showman-additionaltype ofsealing-means, it being understood of course that either sealing means may be used with; either form of my compressor. In the form of sealing means illustratedin Figs. 3 and 4, the rotor l5 takes the shape of "a hemisphere with an obliquely-positioned sector of the sphere removed, and adjacent'the hemispherical portion may be located a cylindrical portion of the same diameter as the hemispherical portion and concentric therewith, extending backwardly toward the shaft IS ashort distance. The only function of the cylindrical portion is to add mechanical trength to the rotor; and hence if itweredesired, that portion might take the form of a'truncated cone. The cap I2 is provided with annular grooves 4|, 42, and 43, grooves 4| and 43 being designated as intake and outlet grooves respectively. Radially aligned with their respective grooves are the intake passageways 30'and 30a and the outlet passageway 31, and connected to the grooves by appropriate means are the intake and outlet connections 28 and 29, respectively.

Between the groove 4| and 43 is the groove 42, and aligned with the latter groove is an annular ridge 44 on the outer'face of the rotor l5 which fitsinto the groove Aland provides a seal between the intake grove 4| and the outlet groove 43. Obviously, other grooves and ridges may be added as required, as for example, between the-inlet groove 4! and the edge of the rotor I 5, or between the outlet groove 43 and'the shaft Iii.

My compressor finds its greatest use in refrigerating systems in which a material in a gaseous phase or in gaseous and liquid phases is compressed to a liquid phase,but it is not limited to -this field. It will be apparent that various materials may-be used in the manufacture'of the compressor and that various dimensions may be used depending upon particular conditions. It is to be understood that my invention is not to be limited to the specific forms or arrangementof parts herein described and shown, or specifically covered by my claims.

I -claim as my invention:

1.'-A rotary; compressor which includes: a housing -a member'in said housing having a concave conical end surface whose-axis is obliquely positioned with respect to the axis of said member and whose base is a plane circle obliquely positioned with respect to the axis of said member; a cone within said housing and axially aligned with said first member; a movable plate in the form of a minor circular sector making a wiping contact with said end surface and extending diametrically across said cone to form with said cone, said end surfaces, and the walls of said housing, a chamber of variable volume; and means to admit and discharge fluid into said chamber of variable volume, said conical surfaces being rotatable with respect to each other.

2. A compressor as described in claim 1 in which said concave conical end surface is surrounded by a lip of varying height whose inner surface is shaped in the form of a portion of a sphere.

3. A compressor as described in claim 1 in which the periphery of said first member adjacent its concave conical end surface is shaped in the form of a portion of a sphere whose radius is equal to the length of the side of said concave conical surface and whose center is at the apex of said conical surface.

4. A rotary compressor which includes: a housing; a member in said housing having a concave conical end surface whose axis is obliquely positioned with respect to the axis-of said member and whose base is a plane circle obliquely positioned with respect to the axis of said member; a cone within said housing coaxial with said first member and against which the high point of said end surface wipes; a movable plate in the form of a minor circular sector, making Wiping contact with said end surface and extending diametrically across said cone, said plate forming with the walls of said housing, said concave surface, and said cone a chamber of variable volume; and means to admit and discharge fluid into said chamber, said conical surfaces being rotatable with respect to each other.

5. A compressor as described in claim 4 in which said concave conical end surface is surrounded by a lipof varying height whose inner surface is shaped in the form of a portion of a sphere.

6. A compressor as described in claim 4 in which the periphery of said first member adjacent its concave conical end surface is shaped in the form of a portion of a sphere whose radius is equal to the length of the side of said concave conical surface and whose center is at the apex of said conical surface. 7

'7. A rotary compressor which includes: a housing; a rotor in said housing having a concave conica1 end surface whose axis is obliquely positioned with respect to the axis of said member and whose base is a plane circle obliquely positioned with respect to the axis of said member; a cone in said housing coaxial with said rtor and against which the high point of said end surface wipes; a movable plate in the form of a minor circular sector whose center is coincident with the apex of said cone, and whose radius is equal to the length of the side of said end surface and making wiping contact therewith, said plate forming with the walls of said housing and said concave and convex conical surfaces a chamber of variable volume; mean for admitting fluid to said chamber while it is expanding; and means to permit fluid to be expelled from said chamber while its volume is being decreased.

8. A compressor as described in claim '7 in which said concave conical end surface is surrounded by a lip of varying height whose inner surface is shaped in the form of a portion of a sphere.

9. A compressor a described in claim '7 in which the periphery of said rotor adjacent its concave conical end surface is shaped in the form of a portion of a sphere whose radius is equal to the length of the side of said concave conical surface and whose center is at the apex of said conical surface.

10. A compressor as described in claim '7 in which said rotor isprovided with sealing means around its periphery to prevent the escape and intermingling of influent and efliuent fluids.

ll. A rotary compressor which includes: a housing; a rotor in said housing having a concave conical end surface whose axis is obliquely positioned with respect to the axis of said member and whose base is a plane circle obliquely positioned with respect to the axis of saidmem ber; a cone in said housing coaxial with said rotor and against which the high point of said end surface wipes; a movable plate in the form :of a minor circular sector whose center is coincident with the apex of said cone and whose radius is equal to the length of the side of said end surface and making wiping contact therewith, said plate forming with the walls of said housing, said end surface, and said cone a chamber of variable volume; means for permitting fluid to enter said chamber while it is expanding; means to permit fluid to be expelled from said chamber while its volume is being decreased; and sealing means including a groove with a sealing member therein between said fluid inlet means and said fluid outlet means.

12. A compressor as described in claim 11 in which said concave'conical end surface is surrounded by a lip of varying height whose inner surface is shaped in the form of a portion of a sphere.

13. A compressor as described in claim 11 in which the periphery of said first member adjacent its concave conical end surface is'shaped in the-form of a portion of a sphere whose radius is equal to the length of the side of said concave conical surface and whose center is at the apex of said conical surface.

DONALD A. FULTON 

